Park cable



May W, E932. Q. A. IFREEHHQKSN PARK CABLE Filed Aug. 7 1929 MM WM Hw/H@3513 l" @Hof/wmf Patented May 17., 1932 UNITED' STATE OTTOABTHURFREDMICKSON, 0F BEN AWGN. PENNElYDWM, ASSIIGNGR T0 NTNAL ELECTRICPRODUCTS CDRPOMTIGN, @E NEW YORK, El Y, A' CORPRATION 0F DELAWARE PMK@ABLE Application died .august A E929. Serial lilo. llldtl.

This invention relates to improvements in cables. Heretofore cables havebeen used which are known as park cables and such. cables as heretoforeconstructed have been made by starting with a lead sheath cable?applying a roving of jute over the lead and over the jute applying twolayers of steel tape and over these steel layers applying other layersof jute and it has been the general practice to treat the jute withpitches, etc., to protect the coverings. The use of such steel tapes isunsatisfactory for 'various reasons, among which may be mentioned thefact that the tapes are subject to corrosion and when they are employedit is difficult to splice the cable because the lea-d is often timespunctured when the steel tape is being removed and furthermore, the useof steel tape aects the flexibility of the cable. Also in the event thata spade or fork is abbed into the cable the sharp edges of the steelfrom the tape frequently puncture the lead.

Heretofore attempts have been made to dispense with the use of steeltapes inpark cables and in lieu thereof cardboard Wrappings have beenemployed. ln practice it has been found necessary to have such cardboardWrappings with a width of about 1% of an inch. Such Width of Wrap ingsof cardboard material has detracted rom the 'HeXibility of the cable.Narrower Wrappings of cardboard material have not been found practicablebecause the cardboard is in laminated form andif it is slit to narrowerwidths say to about 1/8 or kof an inch, such cardboard tape will open upand the laminations Will separate during 'the Wrapping operation. Ifattempt is made to so construct the cardboard and so stick thelaminations together that the laminations will not open up, it has beenfound that when the paper is slit into such narrower widths it is sobrittle that it is practically impossible to wind it around theconductors. Furthermore, when cardboard Wrappings are cmployed suchcardboardmaterial is diiicult to remove because the cardboard materialis relatively stiif and if a subsequent splice is to be made thecardboard strip breaks off at every convolution or so during theunwinding operation and therefore such park cables with cardboard tapeshave heretofore been found dicult to splice.

it is accordingly the object of the present invention to provide animproved form of cable 4which is suitable for the uses where Vpark cablehas heretofore been employed and 'which new cable is not subject to theaforevious constructions.

A further object of the present invention resides in theprovision of acable which is suitable for park cable applications wherein in lieu ofsteel tapes as used heretofore or cardboard strips, convolutions'oftwisted and attened Kraftex paper are employed.

A. further object of the present invention resides in the provision of apark cable with a Wrapping which serves in lieu of steel tapes orcardboard strips as have heretofore been employed and which is strongand durable and which has suthcient strength to enable it to be readilypulled off from the cable without the use of great care in unwinding andWithout the attendant breakage of the Wrappings which has heretoforebeen encountered When cardboard has been employed in lieu of steeltapes.

Further and other objects and advantages Will be hereinafter set forthin connection with the accompanying drawing.

ln the drawingf l0 is the copper conductor which is` preferablytinned-as shown at 11, 12 is the rubber insulation over which is wrappedtape 13. @ver the tape is a lead sheath 14. After the lead sheath isapplied the outer surface of the sheath is covered with an impregna/tingcompound 15.

rlhe next step in the manufacture of the cable is to Wrap upon the layerof compound a layer of hard flattened twisted kraft paper as lgenerallyindicated at 16, thereafter another layer of impregnating compound 17 isapplied and over this layer there is placed another serving or Wrappingof hard ilattened twisted kraft paper as shown at 18. rlfhe convolutionsof this layer extend in opposite directions to the convolutions of layer16. @ver layer 18 there is placed more impregnating compound 19 and ontop of this v mentioned disadvantages and defects of precompound thereis placed a serving or wrapping of saturated (gute 20. After the jutewrapping is applic this wrapping 1s coated with stearin pitch 21constituting a fire retardent and protective coating and over thisstearin pitch coating there is a final coating or layer of wax-likematerial 22 which provides an anti-stick finish for the exterior of thecable.

In the drawing for clarity of illustration certain of the parts areshown exaggerate in thickness. Obviously the tinning 11- is relativelythin and also the impregnating compound layers 15, 17 and 19 in theactual cable permeate into the inside and outside oi flattened twistedpaper servings. Other coatings and compounds are also shown exaggeratedas to thickness.

By employing twisted flattened paper servings the previous objectionablecharacteristics of steel tape Wrappings or of cardboard wrappings areovercome. The twisted fiattened paper provides the desirable shockabsorbing characteristics and at the same time provides a constructionwhich has the maximum of flexibility. The material is also partlcularlyadapted to protect the underlying lead sheath against damagewithouteffecting the flexibility characteristics of the finished cable. Theflattened convolutions of twisted paper furthermore facilitate splicingoperations since the twisted paper wrappings provide a strong durablecord that has sufcient strength to enable it to be pulled off from thecable without the necessity of the splicer going through the unwindingoperation. The splicer merely has to grasp the ends of eitherconvolutions 16 or 18 and draw it off to the desired extent. During suchremoval the kraft material or twisted flattened paper serving does notbreak in the manner that the cardboard strips broke with previousconstructions.

What I claim is:

1. An electrical cable adapted for underground use and having the usualconductor insulation and lead sheath and including in combinationtherewith servings of relatively one serving being reversed with respectto' an adjacent serving and each serving being impregnated from theinside and outside.

4. The invention set forth in claim 3 in which a serving of jute isprovided outside of the flattened paper servings to protect the same. o

5. The invention set forth in claim 3 in which a serving of jute isprovided outsideof the flattened twisted paper servings to protect thesame and which the jute is covered with a coating of a fire retardentmateria-1 over which another coating of wax-like material is placed toprovide an anti-stick slick finish.

6. An electrical cable adapted for underground use and including aninsulated cable and a lead sheath encasing the same and compr1sing inlieu of the usual metal protection for the lead sheath a flexibleexterior protective layer for said sheath, which layer is hard andrelatively rigid and which layer comprises a serving of paperimpregnated with a protecting compound to prevent deterioration of thepaper when the cable is in the ground, said serving being in twisted andin flattened form with the convolutions of the serving relatively narrowin Width and disposed exteriorly of said lead sheath to form therelatively hard protective layer therefor.

In testimony whereof I hereto aflix my signature.

OTTO ARTHUR FREDERICKSON.

hard twisted and flattened paper disposed exteriorly of the lead sheathand therearound said servings constituting by themselves a hardrelatively 'rigid protective layer for the leath sheath.

2.' An electrical cable adapted for underground use and having the usualconductor insulation and lead sheath, and having in combinationtherewith a plurality of impregnated and reversely wrapped servingstherearound formed of twisted flattened paper said reversely wrappedtwisted flattened paper servings constituting by themselves the onlyhard and relatively rigid protective layer for the lead sheath.

3. An electrical cable adapted for under ground use and having the usualconductor

